Patterns on objects in additive manufacturing

ABSTRACT

In an example, a method includes operating, by a processor, on object model data and operating, on a processor, on pattern data. The object model data describes at least part of an object to be generated in additive manufacturing and the pattern data describes an object pattern intended to be formed on at least a portion of the part of the object to be generated in additive manufacturing. The method includes determining, by a processor, control data to control a print agent applicator to apply a pattern of fusing agent onto a part of a layer of build material. The pattern of fusing agent comprises a fusing agent area and a gap area that lacks fusing agent. The gap area corresponds to the object pattern such that no fusing agent is applied to a part of the layer of build material that corresponds to the object pattern.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Application Ser. No.17/256,691, titled PATTERNS ON OBJECTS IN ADDITIVE MANUFACTURING, filedon Dec. 29, 2020, which is incorporated herein in its entirety.

BACKGROUND

Additive manufacturing techniques may generate a three-dimensionalobject through the solidification of a build material, for example on alayer-by-layer basis. In examples of such techniques, build material maybe supplied in a layer-wise manner and the solidification method mayinclude heating the layers of build material to cause melting inselected sub-regions. In other techniques, chemical solidificationmethods may be used.

BRIEF DESCRIPTION OF DRAWINGS

Non-limiting examples will now be described with reference to theaccompanying drawings, in which:

FIG. 1 is a flowchart of an example method of generating an object;

FIG. 2 is a flowchart of an example method of generating an object;

FIG. 3 is an example of a three-dimensional printed object;

FIG. 4 is an example of a three-dimensional printed object;

FIG. 5 is a simplified schematic drawing of an example apparatus foradditive manufacturing;

FIG. 6 is an example of a machine-readable medium in association with aprocessor; and

FIG. 7 is an example tangible (and non-transitory) machine-readablemedium in association with a processor.

DETAILED DESCRIPTION

Additive manufacturing techniques may generate a three-dimensionalobject through the solidification of a build material. In some examples,the build material is a powder-like granular material, which may forexample be a plastic, ceramic or metal powder and the properties ofgenerated objects may depend on the type of build material and the typeof solidification mechanism used. Build material may be deposited, forexample on a print bed and processed layer by layer, for example withina fabrication chamber. According to one example, a suitable buildmaterial may be PA12 build material commercially known as V1R10A “HPPA12” available from HP Inc.

In some examples, selective solidification is achieved throughdirectional application of energy, for example using a laser or electronbeam which results in solidification of build material where thedirectional energy is applied. In other examples, at least one printagent may be selectively applied to the build material, and may beliquid when applied. For example, a fusing agent (also termed a‘coalescence agent’ or ‘coalescing agent’) may be selectivelydistributed onto portions of a layer of build material in a patternderived from data representing a slice of a three-dimensional object tobe generated (which may for example be generated from structural designdata). The fusing agent may have a composition which absorbs energy suchthat, when energy (for example, heat) is applied to the layer, the buildmaterial coalesces and solidifies to form a slice of thethree-dimensional object in accordance with the pattern. In otherexamples, coalescence may be achieved in some other manner

In an example, a suitable fusing agent may be an ink-type formulationcomprising carbon black, such as, for example, the fusing agentformulation commercially known as V1Q60Q “HP fusing agent” availablefrom HP Inc. In some examples, a fusing agent may comprise at least oneof an infra-red light absorber, a near infra-red light absorber, avisible light absorber and a UV light absorber. Examples of print agentscomprising visible light enhancers are dye based colored ink and pigmentbased colored ink, such as inks commercially known as CE039A and CE042Aavailable from HP Inc.

In addition to a fusing agent, in some examples, a print agent maycomprise a coalescence modifier agent, which acts to modify the effectsof a fusing agent for example by reducing or increasing coalescence orto assist in producing a particular finish or appearance to an object,and such agents may therefore be termed detailing agents. In someexamples, detailing agent may be used near edge surfaces of an objectand/or being printed, and/or detailing agent may in other examples beused in part areas to avoid over-fusion (for example when such areas arelarge). According to one example, a suitable detailing agent may be aformulation commercially known as V1Q61A “HP detailing agent” availablefrom HP Inc. A coloring agent, for example comprising a dye or colorant,may in some examples be used as a fusing agent or a coalescence modifieragent, and/or as a print agent to provide a particular color for theobject.

As noted above, additive manufacturing systems may generate objectsbased on structural design data. This may involve a designer generatinga three-dimensional model of an object to be generated, for exampleusing a computer aided design (CAD) application. The model may definethe solid portions of the object, and in some examples properties suchas color, strength, density and the like. To generate athree-dimensional object from the model using an additive manufacturingsystem, the model data may in some examples be processed to generateslices of parallel planes of the model. Each slice may define a portionof a respective layer of build material that is to be solidified orcaused to coalesce by the additive manufacturing system.

FIG. 1 is an example of a method, which may comprise a computerimplemented method, and/or which may comprise a method of determiningobject generation instructions for generating at least part of an objectby additive manufacturing and/or may comprise a method for generating anobject (e.g. a three-dimensional object) by additive manufacturing. Themethod comprises, in block 102, operating, by a processor, on objectmodel data, the object model data describing at least part of an objectto be generated in additive manufacturing.

The object model data may comprise data representing at least a portionof an object to be generated by an additive manufacturing apparatus byfusing a build material. The object model data may for example comprisea Computer Aided Design (CAD) model, and/or may for example comprise aSTereoLithographic (STL) data file, and/or may be derived therefrom. Insome examples, the data may be received over a network, or received froma local memory or the like. In some examples, the data may define theshape of the part of an object, i.e. its geometry. In some examples, thedata may define an appearance property, for example at least oneintended colour, pattern, translucency, gloss or the like. In someexamples the data may define at least one mechanical property, forexample strength, density, resilience or the like. In some examples, thedata may define at least one functional property, for example,conductivity in at least one object portion. Such properties may beassociated with regions of the object, for example a color may bedefined at an object surface.

In some examples, the object may be defined in terms of sub-volumes,each of which represents a region of the object which is individuallyaddressable in object generation. In some examples herein, thesub-volumes may be referred to as voxels, i.e. three-dimensional pixels,wherein each voxel occupies or represents a discrete volume. In someexamples of additive manufacturing, three-dimensional space may becharacterised in terms of such voxels. In some examples, the voxels aredetermined bearing in mind the print resolution of an object generationapparatus, such that each voxel represents a region which may beuniquely addressed when applying print agents, and therefore theproperties of one voxel may vary from those of neighbouring voxel(s). Inother words, a voxel may correspond to a volume which can beindividually addressed by an object generation apparatus (which may be aparticular object generation apparatus, or a class of object generationapparatus, or the like) such that the properties thereof can bedetermined at least substantially independently of the properties ofother voxels. For example, the ‘height’ of a voxel may correspond to theheight of a layer of build material. In some examples, the resolution ofan object generation apparatus may exceed the resolution of a voxel. Ingeneral, the voxels of an object model may each have the same shape (forexample, cuboid or tetrahedral), but they may in principle differ inshape. In some examples, voxels are cuboids having the height of a layerof build material. In some examples, in processing object model datarepresenting an object, each voxel may be associated with properties,and/or object generation instructions, which apply to the voxel as awhole.

In other examples, the object may be described in some other way, forexample using a vector or polygon mesh based model. In some suchexamples, a voxel model may be derived from another model type.

In some examples, the method of FIG. 1 may be carried out on a slice byslice basis. In some examples, each slice may correspond to a layer tobe generated in a layer-by-layer additive manufacturing process. In someexamples, such slices may be slices of a virtual build volume modellingan intended ‘real’ build volume, and may comprise slices taken from morethan one object model. In some examples, the slices may be one voxelthick.

The method 100 comprises, at block 104, operating, by a processor, onpattern data. The pattern data describes an object pattern intended tobe formed on at least a portion of the part of the object to begenerated in additive manufacturing. The object pattern is intended tobe formed on at least a portion of the part of the object described bythe object model data, operated on at block 102. As will be describedwith reference to some examples below, the object pattern described bythe pattern data may comprise an identification code, text, logo,graphic, picture, wear indicator, or any combination thereof. As willalso be described with reference to some examples below, the objectpattern may be intended to be formed on at least an exterior surface, orboundary, of the object to be generated in additive manufacturing. Forexample, the portion of the object to be generated in additivemanufacturing on which the object pattern is intended to be formed maycomprise a slice of the object on an exterior surface, or boundary, ofthe object. In other examples, the object pattern may be intended to beformed on at least an internal region of the object to be generated inadditive manufacturing. For example, the portion of the object to begenerated in additive manufacturing on which the object pattern isintended to be formed may comprise a slice of the object on an interiorof the object (e.g. on an internal region thereof).

Therefore, according to one example, the pattern data describes anobject pattern intended to be formed on an external surface of theobject, and the control data is to control the print agent applicator toapply the pattern of fusing agent onto a part of a layer of buildmaterial corresponding to an external surface of the object.

In one example, block 104 may generate pattern data based on a size(e.g. an area) of the object pattern. For example, block 104 maycomprise generating the pattern data so as to produce the intendedobject pattern, but may create the pattern data so that the size of thebuild material which will correspond to the object pattern is sufficientto be able to be fused by the thermal bleed from parts of the buildmaterial to which fusing agent was applied (when energy is applied tothese parts). In another example, block 104 may comprise receivingpattern data and modifying the received pattern data to adjust the sizeof the gap area such that the gap area will be fused by thermal bleed.In some examples this may involve reducing or shrinking the objectpattern. Therefore, these examples prevent instances where the gap areais too large such that the thermal bleed from the fusing agent area isnot sufficient to fuse all of the gap area. Accordingly, block 104 maycomprise generating pattern data based on the size of the objectpattern, or modifying the pattern data to ensure that the gap area willbe fused by thermal bleed. In one example the method may compriseanalysing the object pattern to determine a size of the gap arearequired to produce the object pattern in the object (e.g. comparing theobject pattern to an acceptable size threshold). In this example themethod may further comprise modifying the size of the gap area so thatthe object pattern may be reproduced, for example if the size thresholdis exceeded (e.g. so that the gap area will sufficiently fuse by thethermal bleed).

According to another example, the pattern data describes an objectpattern intended to be formed on at least an internal portion of theobject, and the control data is to control the print agent applicator toapply the pattern of fusing agent onto a part of a layer of buildmaterial corresponding to an internal portion of the object. In thisexample, the object pattern described by the pattern data may comprise awear indicator, for example, a pattern intended to be formed on aninterior of the object indicating wear (e.g. due to abrasion, erosion,or other physical interactions etc.) to that object. The pattern datamay therefore describe a wear indicator. For example, once the objecthas worn sufficiently to expose enough of a wear indicator this mayindicate that the object needs replacement. In such examples, thepattern data may describe an object pattern intended to be formed on atfirst part of a first slice of the object, the first part being aninternal portion of the object and a second part of a second slice ofthe object, the second part being an internal portion of the object, andthe control data may be to control the print agent applicator to applythe pattern of fusing agent onto a part of a layer of build materialcorresponding to an internal portion of the object. Therefore, theobject pattern may be intended to be formed on at least two slices ofthe object, e.g. may span two slices. For example, the object patternmay describe a first sub-pattern and a second sub-pattern. In oneexample, the first sub-pattern may be intended to be formed on a firstslice of the object and the second sub-pattern may be intended to beformed on a second slice of the object. In another example, the firstand second sub-patterns may each intended to be formed on first andsecond slices of the object. In examples where the object patterndescribes a wear indicator the sub-patterns may be, for example,patterns of different area such as concentric circles. Therefore, theobject pattern described by the pattern data may be intended to beformed in a single slice of the object, or may span multiple slices ofthe object. In each case, the fusing agent may be applied according tothe pattern on a single layer of build material or multiple slices ofbuild material, respectively.

The method 100 comprises, at block 106, determining, by a processor,control data to control a print agent applicator to apply a pattern offusing agent (FA) onto a part of a layer of build material. The patternof fusing agent comprises a fusing agent area and a gap area that lacksfusing agent. The gap area corresponds to the object pattern such thatno fusing agent is applied to a part of the layer of build material thatcorresponds to the object pattern.

Therefore, the control data is to apply a pattern of fusing agent suchthat no fusing agent is applied to areas of build material correspondingto the pattern, but fusing agent is applied to areas of build materialthat do not correspond to the pattern. In this way, when energy (e.g.heat) is applied to the layer of build material to heat and fuse part ofthe layer, the parts of the layer to which fusing agent is applied (e.g.the fusing agent area of the pattern) will fuse, and the parts of buildmaterial to which no fusing agent is applied (e.g. the gap area of thepattern) will sinter (for example, fuse and/or melt) by thermal bleedingfrom the surrounding areas of build material comprising fusing agent. Inother words, in this example, heat may be applied to the layer to fusethe fusing agent area while sintering the gap area.

In examples where the fusing agent comprises black ink (e.g. carbonblack) and the build material comprises white powder, a black fusingagent may be applied to a white build material. In these examples, whenthe black fusing agent is applied according to the fusing agent patternto the white build material the parts of the white build material thatcorrespond to the object pattern (e.g. the gap area) will themselves bewhite (since no black fusing agent is applied to the white buildmaterial) while surrounding areas (fusing agent areas where black fusingagent is applied to the white build material) will be black. In theseexamples, when energy is applied to the layer to heat and fuse thelayer, the build material comprising fusing agent will heat and fusewhile the build material with no fusing agent (corresponding to the gaparea and the object pattern) will fuse by thermal bleed from the fusedbuild material that comprised fusing agent, and the resulting object inthese examples will therefore have the object pattern formed in white inpart of the object, as no fusing agent was applied to parts of the buildmaterial that corresponded to the object pattern. The object pattern inthese examples will therefore be formed in part of the object and willbe of substantially the same colour as the colour of the build material.The surrounding areas (e.g. the areas of the object surrounding theobject pattern which corresponded to parts of the build material towhich fusing agent was applied) will, in these examples, be darker (e.g.black) in appearance.

In some examples, determining object generation instructions maycomprise applying halftoning to voxels associated with object generationparameters to determine object generation or print instructions for thelayer. Halftoning may result in the selection of a particular printagent in a particular location. For example, an object generationparameter may specify an area coverage or contone level for a printagent. A halftoning screen or instructions may be used to makeselections of locations and amounts of print agents to be placed toproduce an intended result (which may be fusion of build material in asimple example, but which may comprise color, transparency,conductivity, density and the like in other examples), for example basedon the area coverage. While halftoning is used in this example, in otherexamples, other techniques may be used. For example, if using piezoprintheads, a drop volume could be directly specified. If the additivemanufacturing technique is or includes a selective laser sinteringtechnique, the method may comprise specifying a power level of a laser.

In one example, block 106 may comprise generating a contone mapdescribing an amount of fusing agent to be applied to areas of buildmaterial according to the object pattern described by the pattern data.For example block 106 may comprise generating a fusing agent contone mapthat describes an amount of fusing agent to be applied to the fusingagent area of the pattern, e.g. an amount of fusing agent to be appliedto an area of a layer of build material corresponding to a voxel of acorresponding slice of the object. In these examples, the area of thelayer of build material may correspond to a voxel in a slice of theobject that surrounds the object pattern in the object. In theseexamples, block 106, may comprise generating a fusing agent contone mapdescribing a number of drops of fusing agent to be applied to a regionof an area of a layer of build material corresponding to a voxel of acorresponding slice of an object. In some examples, the method 100 may(e.g. in block 106) comprise modifying the object model data to accountfor the pattern data (e.g. integrating the pattern data determined atblock 104 with the object model data determined at block 102) and thenblock 106 may comprise generating a contone map to apply fusing agentaccording to the pattern of fusing agent.

For example, block 102 may comprise determining object model data, andblock 104 may comprise determining pattern data and modifying the objectmodel data to include the pattern data (e.g. by integrating the objectmodel data with the pattern data) and then operating (e.g. obtaining,receiving or determining) the modified patterned object data. Block 106in this example may then comprise determining control data to applyfusing agent according to the pattern data which is integrated with theobject model data.

Operating, at block 102 of the method 100, may comprise obtaining,receiving, or determining, by a processor, the object model data.Operating, at block 102, may comprise preparing the object model datafor printing, for example the object model data may be inputted by auser. In another example the object model data may be sent, e.g. from adevice, and block 102 may comprise receiving the data to be subsequentlyprepared for printing. Operating, at block 104 of the method 100, maycomprise obtaining, receiving, or determining, by a processor, thepattern data. In one example, the object model data may comprise thepattern data, and blocks 102 and 104 may be concurrently performed, e.g.the object model data comprising the pattern data may be received by aprocessor and/or inputted by a user. In one example, operating at block102 on the object model data may cause the pattern data to be determinedat block 104. Accordingly, in one example block 102 may comprisedetermining the object model data. In one example block 104 may comprisedetermining the pattern data. As will be described below with referenceto the example of FIG. 2 , a unique identifier may be operated on togenerate the pattern data and/or the object data.

The location of the object pattern in the object may be described by theobject model data and/or the pattern data and/or the unique identifier.

Therefore, in one example the method 100 comprises operating on a uniqueidentifier associated with the pattern data. For example, a uniqueidentifier may be assigned to the pattern data and the method 100 maycomprise receiving the unique identifier, or determining the uniqueidentifier from the object model data, and determining the pattern datafrom the unique identifier.

In some examples, block 106 may comprise determining, by a processor,control data to apply a detailing agent to at least a part of a layer ofbuild material corresponding to a portion of the object. The controldata may be to not apply detailing agent to a part of the build materialcorresponding to a boundary of the gap area, or to a part of the buildmaterial corresponding to an interface between the fusing agent area andthe gap area, since the application of detailing agent to these areasmay reduce the amount of thermal bleed to the parts of the buildmaterial corresponding to the gap area.

The method of FIG. 1 therefore allows an object pattern to be formed inpart of an object to be generated in additive manufacturing havingsubstantially the same colour as the colour of build material used togenerate the object, since no fusing agent is applied to parts of thebuild material corresponding to the object pattern (e.g. the gap area).Additionally, the patterned area in the object generated according tothe method 100 (to which no fusing agent was applied in themanufacturing) will be fused by the thermal bleed from the surroundingareas of build material (to which fusing agent was applied) when heatwas applied during manufacturing to the build material to fuse thelayers of build material. Therefore, once the build material is heatedto generate the object, the gap areas which have had no fusing agentapplied will become the object pattern in the generated object.

FIG. 2 is an example of a method 200, which may comprise a computerimplemented method, and/or which may comprise a method of determiningobject generation instructions for generating at least one object layerby additive manufacturing and/or may comprise a method of additivemanufacturing or for generating an object (e.g. a three-dimensionalobject) by additive manufacturing. The method 200 comprises, in block202, operating on, by a processor, object model data for example asdescribed above in relation to block 102 of method 100.

At block 204 the method 200 comprises operating on a unique identifier.At block 206 the method 200 comprises operating on pattern data, forexample, as described above in relation to block 104 of method 100. Theunique identifier is associated with the pattern data. In one example,the object model data comprises the unique identifier and operating atblock 202 on the object model data may cause the unique identifier to beretrieved and/or generated. In another example, operating, at block 204,comprises obtaining and/or receiving the unique identifier. Block 204 inone example may comprise generating the unique identifier. In oneexample block 204 may comprise determining the pattern data from theunique identifier and block 206 may comprise receiving the pattern data,determined from the unique identifier at block 204. In another example,block 202 may comprise preparing the object model data for printing,block 204 may comprise retrieving the unique identifier from the objectmodel data and block 206 may comprise retrieving the pattern data fromthe unique identifier. The unique identifier may, in some examples,comprise a number.

The method 200 comprises at block 208 integrating the pattern data withthe object model data to generate patterned object data. Accordingly, inthis example the patterned object data comprises the object model datamodified according to the pattern data. For example, the object modeldata may be a sphere and the pattern data may be a logo intended to beformed in the external surface of the object. Block 206 in this examplemay comprise modifying the sphere to include the logo in its externalsurface (at a location determined by the object model data and/or thepattern data).

Block 210 of the method 200 may comprise operating on the patternedobject data. Operating at block 210 may comprise obtaining, receiving ordetermining the patterned object data. According to the example above,where the object model data (the sphere) is integrated with the patterndata (the logo) the patterned object data is the sphere modified withthe logo. Accordingly, block 210 may comprise receiving the “modifiedsphere”. Therefore, block 210 may comprise receiving, at an apparatusfor additive manufacturing, the object to be generated and the objectpattern to be formed on the object.

Block 212 of the method 200 comprises determining, by a processor,control data to control a print agent applicator to apply a pattern offusing agent (FA) onto a part of a layer of build material. The patternof fusing agent comprises a fusing agent area and a gap area that lacksfusing agent. The gap area corresponds to the object pattern such thatno fusing agent is applied to a part of the layer of build material thatcorresponds to the object pattern. Therefore, the control data is toapply a pattern of fusing agent such that no fusing agent is applied toareas of build material corresponding to the object pattern integratedin the modified object data, but fusing agent is applied to areas ofbuild material that do not correspond to the object pattern.

In examples where the fusing agent comprises black ink (e.g. carbonblack) and the build material comprises white powder, a black fusingagent may be applied to a white build material. In these examples, whenthe black fusing agent is applied according to the fusing agent patternto the white build material the parts of the white build material thatcorrespond to the object pattern (e.g. the gap area) will themselves bewhite (since no black fusing agent is applied to the white buildmaterial) while surrounding areas (fusing agent areas where black fusingagent is applied to the white build material) will be black. In theseexamples, when energy is applied to the layer to heat and fuse thelayer, the build material comprising fusing agent will heat and fusewhile the build material with no fusing agent (corresponding to the gaparea and the object pattern) will fuse by thermal bleed from the fusedbuild material that comprised fusing agent. The resulting object inthese examples therefore will have the object pattern formed in part ofthe object but will be white in appearance, as no fusing agent wasapplied to parts of the build material that corresponded to the objectpattern. The object pattern in these examples will therefore be formedin part of the object and will be of substantially the same colour asthe colour of the build material. The surrounding areas (e.g. the areasof the object surrounding the object pattern which corresponded to partsof the build material to which fusing agent was applied) will, in theseexamples, be darker (e.g. black) in appearance.

In one example, block 212 may comprise generating a contone mapdescribing an amount of fusing agent to be applied to areas of buildmaterial according to the object pattern described by the pattern data.For example block 212 may comprise generating a fusing agent contone mapthat describes an amount of fusing agent to be applied to the fusingagent area of the pattern, for example an amount of fusing agent to beapplied to an area of a layer of build material corresponding to a voxelof a corresponding slice of the object. In these examples, the area ofthe layer of build material may correspond to a voxel in a slice of theobject that surrounds the object pattern in the object. In theseexamples, block 212, may comprise generating a fusing agent contone mapdescribing a number of drops of fusing agent to be applied to a regionof an area of a layer of build material corresponding to a voxel of acorresponding slice of an object.

The object pattern described by the pattern data may comprise anidentification code, text, logo, graphic, picture, wear indicator, orany combination thereof.

As described above with reference to the example of FIG. 1 , the objectpattern may be intended to be formed on at least an exterior surface, orboundary, of (a slice of) the object to be generated in additivemanufacturing, or the object pattern may be intended to be formed on atleast an internal region of (a slice of) the object to be generated inadditive manufacturing. The pattern data may therefore describe anobject pattern intended to be formed on an external surface of theobject or an internal portion of the object. The patterned data,operated on at block 210, may therefore comprise the object pattern inan internal portion and/or an external surface of the object. Thecontrol data, determined at block 212, may be to control the print agentapplicator to apply the pattern of fusing agent onto a part of a layerof build material corresponding to an external surface and/or aninternal portion of the object, depending on the location of the objectpattern in/on the object to be generated. The location of the objectpattern may be described by the object model data and/or the patterndata, and/or the unique identifier. The modified object data maydescribe an object pattern intended to be formed on at least two slicesof the object described by the object model data, e.g. may span twoslices. The object pattern may describe a first sub-pattern and a secondsub-pattern. In one example, the first sub-pattern may be intended to beformed on a first slice of the object and the second sub-pattern may beintended to be formed on a second slice of the object. In anotherexample, the first and second sub-patterns may each intended to beformed on first and second slices of the object. In examples where theobject pattern describes a wear indicator the sub-patterns may be, forexample, patterns of different area, concentric circles etc. Therefore,the object pattern described by the pattern data may be intended to beformed in a single slice of the object, or may span multiple slices ofthe object. In each case, the fusing agent may be applied according tothe pattern on a single layer of build material or multiple slices ofbuild material, respectively, and according to the control datadetermined at block 212.

Block 212 may comprise determining, by a processor, control data toapply a detailing agent to at least a part of a layer of build materialcorresponding to a portion of the object, for example as described abovewith reference to block 106 of method 100.

Block 214 comprises applying energy (e.g. heat) to (the part of) thelayer of build material to which the pattern of fusing agent was appliedto fuse the parts of the layer to which fusing agent was applied whilesintering the parts of the layer to which no fusing agent was applied(e.g. the parts of the build material corresponding to the gap area) bythermal bleeding from the surrounding areas of the build material thatcomprise fusing agent. In other words, at block 214, heat may be appliedto the layer to fuse the fusing agent area while sintering the gap area.

Block 214 may comprise printing (or generating) the object using theobject generation instructions. For example, this may comprise forming alayer of build material, applying print agents, for example through useof ‘inkjet’ liquid distribution technologies, in location specified inthe object generation instructions for an object model slicecorresponding to that layer, and applying energy, for example heat, tothe layer. Some techniques allow for accurate placement of print agenton a build material, for example by using print heads operated accordingto inkjet principles of two-dimensional printing to apply print agents,which in some examples may be controlled to apply print agents with aresolution of around 600 dpi, or 1200 dpi. A further layer of buildmaterial may then be formed and the process repeated, with the objectgeneration instructions for the next slice.

In some examples, blocks 202 to 212 may be carried out at leastpartially concurrently with object generation in block 214. As theprocesses of blocks 202 to 212 can be relatively resource heavy in termsof processing power and memory storage, this may make efficient use ofthe resources available.

The method 200 of FIG. 2 therefore allows an object pattern to be formedin part of an object to be generated in additive manufacturing havingsubstantially the same colour as the colour of build material used togenerate the object, since no fusing agent is applied to parts of thebuild material corresponding to the object pattern (e.g. the gap area).Additionally, the patterned area in the object generated according tothe method 200 (to which no fusing agent was applied in themanufacturing) will be fused by the thermal bleed from the surroundingareas of build material (to which fusing agent was applied) when heatwas applied during manufacturing to the build material to fuse thelayers of build material. Therefore, once the build material is heatedto generate the object, the gap areas which have had no fusing agentapplied will become the object pattern in the generated object.

FIG. 3 shows an example of a three-dimensional printed object 300, inthis example a cuboid, which shows an intended placement of an objectpattern 310 formed in an external surface 305 of the object 300.

In some examples, the object 300 may be manufactured using the methods100 or 200 of FIG. 1 or FIG. 2 , respectively. In such examples, whenfusing agent was applied to areas of layers of build material accordingto the fusing agent pattern, no fusing agent was applied to areas of thebuild material corresponding to the object pattern (e.g. the gap areas).Accordingly, the colour of the object pattern 310 formed in the object300 is substantially the same colour as the colour of the build materialused to generate the object 300, since this will have no fusing agentremnant In this example, a coloured fusing agent is applied to a white(or light-coloured) build material. Therefore, the colour of thesurrounding areas 312 (e.g. the areas surrounding the object pattern)are darker in colour as they have fusing agent remnant followingevaporation of the solvent from the applied fusing agent.

Therefore, when the object 300 is manufactured using then method 100 or200, the object pattern described by the pattern data is intended to beformed in an external surface 305 of the object 300 described by theobject model data.

FIG. 4 shows various cross-sectional views through a three-dimensionalprinted object 400, in this example a cuboid, comprising an objectpattern comprising object pattern parts 410 a, 410 b, 410 c each formedon an internal portion of the object 400. In the example shown in FIG. 4the object pattern comprises a wear indicator, and the arrows in FIG. 4denote the object 400 in various stages of wear. In this example, thefirst part 410 a of the object pattern is a pattern of a first area. Thesecond part 410 b is a pattern of a second area and the third part 410 cis a pattern of a third area. The first area is less than the secondarea which is less than the third area. The object 400 comprises anexternal surface 410. Each of the three pattern parts 410 a-c are formedon an internal portion of the object 400. As shown in FIG. 4 , theobject 400 comprises three portions 411, 412 and 413. The first portion411 is revealed when the external surface 410 has worn away, eroded ordeformed etc. Therefore, at least a part of the first portion 411 isinternal to the object (relative to the external surface 410) (they mayof course share a boundary, e.g. at their edges). The second portion 412is revealed when the first portion 411 has worn away, eroded or deformedetc. Therefore, at least a part of the second portion 412 is internal tothe object and closer to a centre of the object than a correspondingpart of the first portion 411. The first portion 413 is revealed whenthe second portion 412 has worn away, eroded or deformed etc. Therefore,at least a part of the third portion 413 is internal to the object andcloser to a centre of the object than a corresponding part of the secondportion 412.

For example, a respective part of each of the three portions 411-413 mayrepresent three spatial shells each representing a corresponding levelor layer of the region of the object 400. The shells may have any shape,and do not necessarily conform to the shape of the outer profile of theobject 400. For example, the three portions 411-413 may be a sequence ofshells nested within the external surface 410 of the object 400. Theymay be at different locations of the object 400 or, as shown in the FIG.4 example, at different depths. Each portion 411-413 thereforerepresents a respective different level (e.g. a level of depth) of theobject 400. Each portion 411-413 may represent a different level of theobject (e.g. first portion 411 may represent a first level, etc.) withthe first level 411 being the level that is closest to the outer surface410 of the object 400 and/or farthest away from a centre of the object400, and the third level 413 being the level that is farthest away fromthe outer surface 410. The portions 411, 412 and 413 may representrespective portions of the object 400 at increasing depths into theobject or, equivalently, at increasing distances from the outer surface410 of the object 400. Erosion of the outer surface 410 may expose thefirst portion or level 411. Erosion of the first portion or level 411may expose the second portion or second level 412. Erosion of the secondportion or level 412 may expose the third portion or third level 413.

Therefore, the wear indicator pattern comprising first, second, andthird parts 410 a, 410 b, and 410 c is progressively exposed as theobject 400 erodes or wears away. As the object 400 wears away toprogressively expose the first, second and third internal portions 411,412, 413 of the object 400, the first, second and third object parts 410a, 410 b, 410 c are exposed. Therefore, as the object 400 progressivelyerodes or wears away, the object pattern parts of increasing area areprogressively exposed. In this way a user may visually identify the ageof the part based on the area of the part of the object pattern exposed.

In some examples, the object 400 may be manufactured using the methods100 or 200 of FIG. 1 or FIG. 2 , respectively. In such examples, whenfusing agent was applied to areas of layers of build material accordingto the fusing agent pattern, no fusing agent was applied to areas of thebuild material corresponding to the object pattern (e.g. the gap areas).Accordingly, the colour of each object pattern part 410 a-c formed in arespective internal part 411-413 of the object 400 are eachsubstantially the same colour as the colour of the build material usedto generate the object 400, since this will have no fusing agent remnantIn this example, a coloured fusing agent is applied to a white (orlight-coloured) build material. Therefore, the colour of the surroundingareas (e.g. the areas surrounding the object pattern parts 411-413) aredarker in colour as they have fusing agent remnant following evaporationof the solvent from the applied fusing agent.

Therefore, when the object 400 is manufactured using the method 100 or200, the object pattern described by the pattern data is intended to beformed in an internal portion 411, 412, 413 of the object 400 describedby the object model data. In the example of FIG. 4 , the object patternmay be intended to be formed on a plurality of slices of the object 400.For example, each portion 411, 412, 413 may be a part of a respectiveslice of the object (e.g. a solidified layer of build material) or maycomprise part of a plurality of slices. In the latter case, whengenerating the object 400 fusing agent may be applied according to thefusing agent pattern onto to respective parts of a plurality ofdifferent layers of build material.

FIG. 5 shows an apparatus 500 comprising processing circuitry 502. Theprocessing circuitry 502 comprises an interface 504 and a control datamodule 506.

The interface 504 is to operate on object model data and pattern data,the object model data describing at least part of an object to begenerated in additive manufacturing and the pattern data describing anobject pattern intended to be formed on at least a portion of the partof the object. The control data module 506 is to generate control datato control a 3D printer to generate the object by selectively fusingsuccessive layers of build material, and wherein the control data is tocontrol a print agent applicator to apply a pattern of fusing agent ontoa part of a layer of build material, the pattern of fusing agentcomprising a fusing agent area and a gap area that lacks fusing agent,wherein the gap area corresponds to the object pattern such that nofusing agent is applied to a part of the layer of build material thatcorresponds to the object pattern.

In one example the control data is to generate a contone map describingan amount of fusing agent to be applied to areas of build materialaccording to the object pattern described by the pattern data. In oneexample the interface is to operate on a unique identifier beingassociated with the pattern data, to determine the pattern data.

The object pattern described by the pattern data may comprise anidentification code, text, logo, graphic, picture, wear indicator, orany combination thereof, as described above.

FIG. 6 shows an example of 3-D printing apparatus 600. The 3-D printingapparatus 600 comprises the apparatus 500 of FIG. 5 . 3-D printingapparatus 600 comprises a print agent applicator 602. The print agentapplicator 602 is to apply, under control of the control data generatedby the control data module fusing agent to an area of build materialaccording to the fusing agent pattern. Therefore the print agentapplicator 602 is to apply, under control of the control data, no fusingagent to areas of build material that correspond to the gap region, andfusing agent to surrounding areas of build material.

In some examples, the 3-D printing apparatus 600 may operate under thecontrol of control data generated based on the print instructions togenerate at least one object in a plurality of layers according to thegenerated control data/print instructions. The 3-D printing apparatus600 may generate an object in layer-wise manner by selectivelysolidifying portions of layers of build materials. The selectivesolidification may in some examples be achieved by selectively applyingprint agents, for example through use of ‘inkjet’ liquid distributiontechnologies, and applying energy, for example heat, to the layer. The3-D printing apparatus 600 may comprise additional components not shownherein, for example a fabrication chamber, a print bed, print head(s)for distributing print agents, a build material distribution system forproviding layers of build material, energy sources such as heat lampsand the like, which are not described in detail herein.

The processing circuitry 502, and/or the 3-D printing apparatus 600 maycarry out any or any combination of the blocks of the methods 100 and/or200 shown in FIG. 1 or FIG. 2 , respectively. The apparatus 500 or theapparatus 600 may be to manufacture the object 300 or the object 400 asshown in FIGS. 3 and 4 , respectively.

FIG. 7 shows an example tangible (and non-transitory) machine-readablemedium 702 in association with a processor 704. The tangiblemachine-readable medium 702 comprises instructions 706 which, whenexecuted by the processor 704, cause the processor 704 to carry out aplurality of tasks. The instructions 706 comprise instructions 708 tooperate on machine-readable object model data describing an object to bemanufactured and machine-readable pattern data describing a patternintended to be formed on a portion of the object to be manufactured. Theinstructions 706 comprise instructions 710 to generate printinstructions for generating the object described by the machine-readableobject model data. The instructions 706 comprise instructions 712 togenerate print agent data to cause no fusing agent to be applied to aregion of build material corresponding to the pattern described by themachine-readable pattern data.

In one example, the instructions 706 may comprise instructions togenerate a contone map describing an amount of fusing agent to beapplied to areas of build material according to the pattern described bythe machine-readable pattern data.

The instructions 706 may comprise instructions to operate on a uniqueidentifier associated with the machine-readable pattern data. Theinstructions 708 to operate on the machine-readable object model dataand the machine-readable pattern data may comprise instructions toobtain, receive, determine and/or generate the machine-readable objectmodel data and/or the machine-readable pattern data. The instructions706 may comprise instructions to integrate or modify themachine-readable object model data with the machine-readable patterndata.

The machine-readable medium 702 may comprise instructions to performany, or a combination of, the blocks of the methods 100 or 200 as setout in FIG. 1 or 2 , respectively; and/or to provide the interface 504and/or the control data module 506 of the examples of FIG. 5 or 6 .

Some examples herein relate to producing a pattern on an object havingthe same, or substantially similar, colour as the build material used togenerate that object, since the parts of build material corresponding tothe pattern are not inked with a fusing agent. Those parts of the buildmaterial may be thin enough to still be fully fused by thermal bleedfrom the surrounding areas that are inked with fusing agent. As aresult, the pattern (which, as above, may in some examples be a wearindicator) has the intrinsic colour of the build material, whereas therest of the object has the colour of the fusing agent. This resultingcolour contrast is able to provide a good visual indication of thepattern (and in examples where the pattern is a wear indicator,geometric wear), and because the (non-inked) patterned parts of theobject are fully fused, the properties of the object are not affected.Some examples herein are therefore able to produce a colour contrastwithout requiring multi-colour printing or using multiple materials(e.g. without requiring the use of a coating or a binder), withoutaffecting the mechanical or thermal properties of the object, oradditional time and cost.

Examples in the present disclosure can be provided as methods, systemsor machine-readable instructions, such as any combination of software,hardware, firmware or the like. Such machine-readable instructions maybe included on a computer readable storage medium (including but notlimited to disc storage, CD-ROM, optical storage, etc.) having computerreadable program codes therein or thereon.

The present disclosure is described with reference to flow charts and/orblock diagrams of the method, devices and systems according to examplesof the present disclosure. Although the flow diagrams described aboveshow a specific order of execution, the order of execution may differfrom that which is depicted. Blocks described in relation to one flowchart may be combined with those of another flow chart. It shall beunderstood that each block in the flow charts and/or block diagrams, aswell as combinations of the blocks the flow charts and/or blockdiagrams, can be realized using machine-readable instructions.

The machine-readable instructions may, for example, be executed by ageneral-purpose computer, a special purpose computer, an embeddedprocessor or processors of other programmable data processing devices torealize the functions described in the description and diagrams. Inparticular, a processor or processing apparatus may execute themachine-readable instructions. Thus, functional modules of the apparatus(such as the feasibility assessment module 504 and/or the printinstructions module 506) may be implemented by a processor executingmachine-readable instructions stored in a memory, or a processoroperating in accordance with instructions embedded in logic circuitry.The term ‘processor’ is to be interpreted broadly to include a CPU,processing unit, ASIC, logic unit, or programmable gate array etc. Themethods and functional modules may all be performed by a singleprocessor or divided amongst several processors.

Such machine-readable instructions may also be stored in a computerreadable storage that can guide the computer or other programmable dataprocessing devices to operate in a specific mode.

Machine-readable instructions may also be loaded onto a computer orother programmable data processing device(s), so that the computer orother programmable data processing device(s) perform a series ofoperations to produce computer-implemented processing, thus theinstructions executed on the computer or other programmable devicesrealize functions specified by block(s) in the flow charts and/or theblock diagrams.

Further, the teachings herein may be implemented in the form of acomputer software product, the computer software product being stored ina storage medium and comprising a plurality of instructions for making acomputer device implement the methods recited in the examples of thepresent disclosure.

While the method, apparatus and related aspects have been described withreference to certain examples, various modifications, changes,omissions, and substitutions can be made without departing from thespirit of the present disclosure. It is intended, therefore, that themethod, apparatus and related aspects be limited by the scope of thefollowing claims and their equivalents. It should be noted that theabove-mentioned examples illustrate rather than limit what is describedherein, and that those skilled in the art will be able to design manyalternative implementations without departing from the scope of theappended claims. Features described in relation to one example may becombined with features of another example.

The word “comprising” does not exclude the presence of elements otherthan those listed in a claim, “a” or “an” does not exclude a plurality,and a single processor or other unit may fulfil the functions of severalunits recited in the claims.

The features of any dependent claim may be combined with the features ofany of the independent claims or other dependent claims.

1. A method comprising: operating, by a processor, on object model data,the object model data describing at least part of an object to begenerated in additive manufacturing; operating, by the processor, onpattern data describing an object pattern intended to be formed on atleast a portion of the part of the object to be generated in additivemanufacturing, wherein the object pattern comprises a shape or text; anddetermining, by the processor, control data to control a print agentapplicator to apply a pattern of fusing agent onto a part of a layer ofbuild material, the pattern of fusing agent comprising a fusing agentarea and a gap area that lacks fusing agent, wherein the gap areacorresponds to the object pattern such that no fusing agent is appliedto a part of the layer of build material that corresponds to the objectpattern, wherein the build material in the gap area is fused by thermalbleed from the fusing agent area that surrounds the build material inthe gap area.
 2. The method according to claim 1, wherein determiningthe control data comprises generating a contone map describing an amountof fusing agent to be applied to areas of build material according tothe object pattern described by the pattern data.
 3. The methodaccording to claim 1, further comprising: operating, by the processor,on patterned object data, the patterned object data comprising theobject model data modified according to the pattern data.
 4. The methodaccording to claim 3, further comprising: integrating the pattern datawith the object data to generate the patterned object data.
 5. Themethod according to claim 1, wherein the object pattern comprises ashape or text on an exterior surface of the object.
 6. The methodaccording to claim 1, wherein the pattern data describes the objectpattern intended to be formed on an external surface of the object, andwherein the control data is to control the print agent applicator toapply the pattern of fusing agent onto a part of a layer of buildmaterial corresponding to the external surface of the object.
 7. Themethod according to claim 1, wherein the pattern data describes theobject pattern intended to be formed on at least an internal portion ofthe object, wherein the control data is to control the print agentapplicator to apply the pattern of fusing agent onto a part of a layerof build material corresponding to the internal portion of the object.8. The method according to claim 1, wherein the pattern data describesthe object pattern intended to be formed on a first part of a firstslice of the object, the first part being part of an internal portion ofthe object and a second part of a second slice of the object, the secondpart being another part of the internal portion of the object whereinthe control data is to control the print agent applicator to apply thepattern of fusing agent onto a part of a layer of build materialcorresponding to the internal portion of the object.
 9. The methodaccording to claim 1, further comprising: operating, by a processor, ona unique identifier, the unique identifier being associated with thepattern data, to determine the pattern data.
 10. The method according toclaim 1, further comprising applying energy to the part of the layer ofbuild material comprising the pattern of fusing agent to fuse the partsof the layer comprising fusing agent while sintering the gap area bythermal bleeding from the parts of the layer comprising fusing agent.11. An apparatus comprising: processing circuitry, wherein theprocessing circuitry comprises: an interface to operate on object modeldata and pattern data, the object model data describing at least part ofan object to be generated in additive manufacturing and the pattern datadescribing an object pattern intended to be formed on at least a portionof the part of the object, wherein the object pattern comprises a shapeor text; and a control data module to generate control data to control a3D printer to generate the object by selectively fusing successivelayers of build material, and wherein the control data is to control aprint agent applicator to apply a pattern of fusing agent onto a part ofa layer of build material, the pattern of fusing agent comprising afusing agent area and a gap area that lacks fusing agent, wherein thegap area corresponds to the object pattern such that no fusing agent isapplied to a part of the layer of build material that corresponds to theobject pattern, wherein the build material in the gap area is fused bythermal bleed from the fusing agent area that surrounds the buildmaterial in the gap area.
 12. The apparatus according to claim 11,wherein the control data is to generate a contone map describing anamount of fusing agent to be applied to areas of build materialaccording to the object pattern described by the pattern data.
 13. Theapparatus according to claim 11, wherein the interface is to operate ona unique identifier being associated with the pattern data, to determinethe pattern data.
 14. The apparatus according to claim 11, whichcomprises a 3D printing apparatus.
 15. The apparatus according to claim11, wherein the object pattern comprises a shape or text on an exteriorsurface of the object.
 16. A non-transitory computer-readable storagemedium comprising a set of computer-readable instructions storedthereon, which, when executed by a processor of a printing system causethe processor to: operate on machine-readable object model datadescribing an object to be manufactured and machine-readable patterndata describing a pattern intended to be formed on a portion of theobject to be manufactured, wherein the pattern comprises a shape ortext; generate print instructions for generating the object; andgenerate print agent data to cause no fusing agent to be applied to aregion of build material corresponding to the pattern described by themachine-readable pattern data, wherein the region of build material withno fusing agent is fused by thermal bleed from an area of build materialwith a fusing agent that surrounds the region of build material with nofusing agent.
 17. The non-transitory computer-readable storage mediumaccording to claim 16, wherein the instructions, when executed by theprocessor, cause the processor to: generate a contone map describing anamount of the fusing agent to be applied to areas of build materialaccording to the pattern described by the machine-readable pattern data.18. The non-transitory computer-readable storage medium according toclaim 16, wherein the object pattern comprises a shape or text on anexterior surface of the object.